Contribution of hydrological models and GIS to the study of the impact of climate variability and land-use change on water resources of the Volta watershed in Côte d’Ivoire

The water resources of the Volta watershed in Cote d'Ivoire are often destined for human consumption and the development of agro-pastoral or industrial activities. This study aims to characterize climate variability and its consequences and to analyze the dynamics of land-use on the water resources of this basin, from hydrological models and GIS. Since the rainfall decline, observed during the years 1963 to 1970, several periods of drought have been observed and have caused the disappearance of plant species, some water bodies and some areas of groundwater recharge. The determined rainfall during the period 1936 to 2002 is 1102.86mm with only a surplus of 87.30mm of which 5.68% is destined for surface runoff and 2.23% for groundwater recharge. The flow rate of rivers from 1990 to 1993 is 1.39m3.s-1 with a drying up coefficient of 6.95.10-2 j-1 and a mobilized water volume by aquifers of only 0.028km3. These parameters determine a low hydraulic potential of the basin. Dominated by tree savannah or shrubby savannah (81.17%) in 1990, the degradation of the vegetation cover of the basin has had adverse effects on water resources. However, until the year 2000, the regeneration of gallery forest and dense tree savannah (from 8.48% to 16.01%) will favor the reconstitution of some water bodies. Thus, for an effective rehabilitation of the environment, it will be necessary to reinforce the strategic plans for adaptation to climate variability.